linux-kernel - Re: [PATCH] proc: don't show nonexistent capabilities (v2)

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Message-ID: <20121008154711.GA16261@sergelap>
Date:	Mon, 8 Oct 2012 10:47:11 -0500
From:	Serge Hallyn <serge.hallyn@...onical.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	Andrew Vagin <avagin@...nvz.org>, linux-kernel@...r.kernel.org,
	"Andrew G. Morgan" <morgan@...nel.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH] proc: don't show nonexistent capabilities (v2)

Quoting Kees Cook (keescook@...omium.org):
> On Sun, Oct 7, 2012 at 2:56 AM, Andrew Vagin <avagin@...nvz.org> wrote:
> > Without this patch it is really hard to interpret a bounding set,
> > if CAP_LAST_CAP is unknown for a current kernel.
> >
> > Non-existant capabilities can not be deleted from a bounding set
> > with help of prctl.
> >
> > E.g.: Here are two examples without/with this patch.
> > CapBnd: ffffffe0fdecffff
> > CapBnd: 00000000fdecffff
> >
> > I suggest to hide non-existent capabilities. Here is two reasons.
> > * It's logically and easier for using.
> > * It helps to checkpoint-restore capabilities of tasks, because tasks
> > can be restored on another kernel, where CAP_LAST_CAP is bigger.
> >
> > v2: Non-existent capabilities can not be removed from creds, because
> >     in this case user cannot set all=eip. This patch cleans up non-existent
> >     capabilities from content of /proc/pid/status
> >
> > Cc: Andrew G. Morgan <morgan@...nel.org>
> > Cc: Serge Hallyn <serge.hallyn@...onical.com>

Basic capsh tests seem to have no problem with it.

Thanks, Andrew.

Reviewed-by: Serge E. Hallyn <serge.hallyn@...onical.com>

> > Cc: Pavel Emelyanov <xemul@...allels.com>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Cc: Kees Cook <keescook@...omium.org>
> > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> > Signed-off-by: Andrew Vagin <avagin@...nvz.org>
> 
> Seems sensible to me.
> 
> Reviewed-by: Kees Cook <keescook@...omium.org>
> 
> -Kees
> 
> -- 
> Kees Cook
> Chrome OS Security
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